분산염색에서 Cotelomer 타입 계면 활성제의 응용

이재호,최해욱,정영진,황대연,최영호,이언필,Lee, Jae-Ho,Choi, Hae-Wook,Jung, Young-Jin,Hwang, Dae-Youn,Choi, Young-Ho,Lee, Eon-Pil 한국섬유공학회 2010 한국섬유공학회지 Vol.47 No.1

Multi-chain surfactants usually form micelles more easily than single-chain surfactants due to their low surface tension and low solubility in water. In this study we prepared cotelomers of multi-alkylated nonionic surfactants with a molecular structure $xR_nMA$-yVA (x; hydrophobic group, y; hydrophilic group, MA; methacrylic ester, VA; vinyl alcohol, R; alkyl group) and investigated their properties as surfactants for the disperse dyeing of cellulose acetate, nylon 6, and PET fibers. Some cotelomers were synthesized via a radical polymerization of vinyl monomers MA and VA using azobisisobutyronitrile (AIBN) as an initiator. The ratio of x/y and degree of polymerization of $xR_nMA$-yVA with an alkyl chain length (n) of 4 or 6 were controlled by adjusting the ratio of thiol to monomers. We found that a cotelomer with a degree of polymerization 9.9 showed better dispersing performances than cotelomer with a degree of polymerization 4.4 or 12.5, and that the degree of dispersion increased to a certain level and then decreased as concentration of cotelomer increased. The highest value of dye uptake for the three fibers was obtained when using a cotelomer with a monomer unit ratio (x/y) of 0.2 and 0.5 g/l of concentration was 0.5 g/l.

T-형 $Ca^{2+}$ 채널 길항제인 Mibefradil을 첨가한 인간 정자의 첨체반응 관찰

이재호,손원영,이정하,이인선,김영찬,한징택,Lee, Jae-Ho,Son, Weon-Young,Lee, Jung-Ha,Lee, In-Sun,Kim, Young-Chan,Han, Ching-Tack 대한생식의학회 2000 Clinical and Experimental Reproductive Medicine Vol.27 No.1

Objective: The sperm acrosome reaction is a $Ca^{2+}$-dependent exocytotic event that is triggered by adhesion to the mammalian egg's zona pellucida. Previous studies suggested a role of $Ca^{2+}$ channels in acrosome reactions. This study was conducted to investigate the T-type calcium channel is operated in acrosome reaction of human spermatozoa. Method: Human semen samples were obtained from healthy donors with normal criteria. The spermatozoa were divided into five groups: Group 1 were non-treated as a control; Group 2 where spermatozoa were exposed to 5 ${\mu}M$ $Ca^{2+}$ A23187 $(Ca^{2+}i)$; Group 3 where spermatozoa were exposed 5 ${\mu}M$ $Ca^{2+}i$ and mibefradil; Group 4 where spermatozoa were exposed 5 ${\mu}M$ $Ca^{2+}i$ and nifedipine, and Group 5 where spermatozoa were treated with 5 ${\mu}M$ $Ca^{2+}i$ and both of mibefradil and nifedipine. Spermatozoa in all groups were retrieved after incubation for 15 and 30 minutes at $37^{\circ}C$. After staining with PSA-FITC, fluorescence was observed under a fluorescence microscope, and AR was evaluated on a total>100 spermatozoa/side. Result and Conclusion: We observed on acrosome reaction inhibition rate in human spermatozoa the various of concentration of mibefradil, nifedipine. Maximum response was noted with 1.0 ${\mu}M$ mibefradil and the decrease of acrosome reaction inhibition rate 45%. Nifedipine in acrosome reaction inhibition rate was only about 25%. The $Ca^{2+}i$-induced AR of spermatozoa was significantly suppressed by mibefradil. Incidence of the suppression was depending on concentration of mibefradil. Results from the present study suggest that the human spermatozoa possess T-type channel. The observation that reversible inhibitor of T channels in male germ cells provides a new mechanism of contraceptive action.

Flash EEPROM에서 부유게이트의 도핑 농도가 소거 특성에 미치는 영향

이재호,신봉조,박근형,이재봉,Lee, Jae-Ho,Shin, Bong-Jo,Park, Keun-Hyung,Lee, Jae-Bong 대한전자공학회 1999 電子工學會論文誌, D Vol.d36 No.11

Flash EEPROM에서 칩 전체나 또는 칩의 한 블록에 속에 있는 모든 셀들의 소거는 Fowler-Nordheim (FN) 터널링 방식을 사용하여 일괄적으로 수행되고 있다. 이러한 FN 터널링에 의한 소거는 self-limited 공정이 아니기 때문에 일부의 셀들이 심하게 과소거되는 문제가 자주 발생하고 있다. 본 논문에서는 이러한 과소거 문제를 해결하기 위한 부유게이트의 최적 도핑 농도에 관하여 연구하였다. 이러한 연구를 위하여 다양한 도핑 농도를 갖는 n-type MOSFET과 MOS 커패시터를 제작하였고, 이 소자들의 전기적인 특성들을 측정 및 분석하였다. 실험 결과, 부유게이트의 도핑 농도가 충분히 낮다면 ($1.3{\times}10^{18}/cm^3$ 이하) 과소거가 방지될 수 있음을 볼 수 있었다. 이는, 소거시 부유게이트에 저장되었던 전자들의 대부분이 빠져나가면 부유게이트에 공핍층이 형성되어 부유게이트와 소스 사이의 전압 차가 감소하고 따라서 소거가 자동적으로 멈추기 때문이라고 판단된다. 반면에 부유게이트의 도핑 농도가 너무 낮을 경우 ($1.3{\times}10^{17}/cm^3$ 이하)에는 문턱 전압과 gm의 균일도가 크게 나빠졌는데, 이는 부유게이트에서 segregation으로 인한 불순물의 불균일한 손실에 의한 것이로 판단된다. 결론적으로 Flash EEPROM에서 과소거 현상을 방지하고 균일한 문턱 전압과 gm을 갖기 위한 최적의 부유게이트의 도핑 농도는 $1.3{\times}10^{17}/cm^3$에서 $1.3{\times}10^{18}/cm^3$의 범위인 것으로 발견되었다. All the cells on the whole memory array or a block of the memory array in the Flash EEPROM's are erased at the same time using Fowler-Nordheim (FN) tunneling. some of the cels are often overerased since the tunneling is not a self-limited process. In this paper, the optimum doping concentration of the floating gate solve the overerase problem has been studied. For these studies, N-type MOSFETs and MOS capacitors with various doping concentrations of the gate polysilicon have been fabricated and their electrical characteristics have been measured and analyzed. As the results of the experiment, it has been found that the overerase problem can be prevented if the doping concentration of the floating gate is low enough (i.e. below $1.3{\times}10^{18}/cm^3$). It is because the potential difference between the floating gate and the source is lowered due to the formation of the depletion layer in the floating gate and thus the erasing operation stops by itself after most of the electrons stored in the floating gate are extracted. On the other hand, the uniformity of the Vt and the gm has been significantly poor if the coping concentration of the floating, gate is too much lowered (i.e. below $1.3{\times}10^{17}/cm^3$), which is believed to be due to nonuniform loss of the dopants from the nonuniform segregation in the floating gate. Consequently, the optimum doping concentration of the floating gate to suppress the overerase problem and get the uniform Vt and has been found to range from $1.3{\times}10^{17}/cm^3$ to $1.3{\times}10^{18}/cm^3$ in the Flash EEPROM.

WiBro 환경에서 Overlay 기반의 Mobile IPv6 이동성 구현 및 성능 시험에 관한 연구

이재호,류형근,이재준,강선무,이재용,Lee, Jae-Ho,Ryu, Hyung-Keun,Lee, Jae-Jun,Kang, Sun-Moo,Lee, Jai-Yong 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.6b

A Mobile IP is considered for the efficient mobility function in IEEE 802.16/WiBro environment. However, during the deployment of WiBro, only some of the ACRs(Access Control Router) can support the Mobile IP function. Therefore, a WiBro network can not support the mobility function for the mobile node. In this paper, we implement an overlay-based Mobile IP function and measure the performance through a field trial. Moreover, we evaluate the possibility of commercial deployment and suggest areas that need to be improved. IEEE 802.16/WiBro 환경에서 효율적인 이동성을 위하여 Mobile IP 적용이 고려되고 있다. 하지만 WiBro 확산과정에서 Mobile IP 이동성을 지원하는 ACR과 지원하지 못하는 ACR이 혼재된 상황이 존재하고 있으며, 이럴 경우 단말의 이동성은 보장받기 어렵게 된다. 본 논문에서는 이러한 WiBro 환경에서 지속적인 단말 이동성을 지원하기 위하여 Overlay 기반의 Mobile IP 이동성을 실제로 구현하고 이에 대한 성능 시험을 시행한 후 현장 적용 가능성을 검증하고 향후 개선 필요 사항을 도출하였다.

아라미드 표면처리에 의한 실리콘/불소 고무와의 접착성 연구

이재호,이재동,박성민,이종우,Lee, Jae-Ho,Lee, Jae-dong,Park, Sung-min,Lee, Jong-woo 한국섬유공학회 2018 한국섬유공학회지 Vol.55 No.5

The interfacial adhesion property between aramid and rubber is a very important factor when aramid is applied as a reinforcing material for automotive heat-resistant hoses. This study examined the improvement of interfacial adhesion between aramid and rubber by applying plasma and a coupling agent to m-aramid. The SEM, AFM, and XPS characteristics were examined based on the plasma treatment conditions. The plasmatreated aramid was then treated with the coupling agent to analyze the interfacial adhesion with silicon, fluorine, and hybrid rubber. The plasma treatment resulted in an increase in the surface roughness of the aramid, and the mechanical properties of the aramid fabric decreased because the surface of the aramid was fibrillated. Moreover, the interfacial adhesion between aramid and rubber increased by 16.2% with the use of the coupling agent and plasma treatment.

초음파자동검사용 구동 모듈 및 C-Scan 프로그램 개발

이재호,Lee, Jae-Ho 한국비파괴검사학회 2010 비파괴 Vol.11 No.-

회원기고 - 신비한 산양산삼 40가지 이야기

이재호,Lee, Jae-Ho 한국산림경영인협회 2010 山林經營 Vol.196 No.-

Duty Cycle 기반의 WSN MAC을 위한 트래픽 환경에 따른 가변 Wakeup Period 기법 제안

이재호,엄두섭,Lee, Jae-Ho,Eom, Doo-Seop 대한전자공학회 2012 전자공학회논문지 Vol.50 No.8

센서 네트워크는 센서가 설치된 지역에서 감지된 데이터를 무선으로 전달하는 기술로서, 기존 방식과 달리 에너지 효율이 매우 중요한 성능요소이다. 이러한 특성에 따라 많은 WSN MAC 프로토콜에서는 Wakeup과 Sleep을 반복하여 수행하는 Duty Cycle 기법을 활용하고 있지만, 고정적인 Wakeup 구간의 설정에 따라 획일화된 에너지 성능과 수신 성공률로 인하여 성능이 제한적이다. 본 논문에서는 이러한 Duty Cycle 기반의 MAC 프로토콜을 개선하기 위하여, 채널 환경에 따라 동적으로 Wakeup 구간을 가변화시키는 기법을 제안한다. 제안하는 방식은 트래픽이 높은 환경에서 Wakeup 구간을 증가시켜 수신 성공률을 높이고, 트래픽이 낮은 환경에서 Wakeup 구간을 줄여 에너지 성능을 향상시켰다. 또한 본 논문에서는 제안하는 방식의 성능에 대한 효율적인 평가를 위하여 기존 동기식 및 비동기식 MAC의 결과와 제안방식을 적용한 MAC의 결과를 비교하고 이를 분석하였다. The energy efficiency is extremely significant in Wireless Sensor Networks (WSN) which deliver the data sensed in the sensor field, using wireless communications. Under the characteristics of WSN, many MAC protocols employ the Duty Cycle mechanism which continuously operates Wakeup and Sleep periods, for the energy efficiency. However, constant Wakeup period in general Duty Cycle incurs the limited performance of the energy efficiency and the receiving ratio. For addressing this, we design and propose a new scheme called Variable Wakeup Period, considering local traffic conditions. Our scheme enhances receiving ratio by increasing Wakeup period under the high traffic condition, and makes high energy efficiency by decreasing Wakeup period under the otherwise condition. In addition, we evaluate the performance of our scheme by performing the simulation, which experiments the previous synchronous and asynchronous MAC protocols, and which also experiments the same protocols with the proposed scheme, for comparative evaluations.

Pt 나노분말이 분산된 SiO₂ 박막의 구조 및 전기적 특성 제어

이재호,신인주,이성우,김형철,최병준,Lee, Jae Ho,Shin, In Joo,Lee, Sung Woo,Kim, Hyeong Cheol,Choi, Byung Joon 한국분말야금학회 2014 한국분말재료학회지 (KPMI) Vol.21 No.5

Pt nanopowder-dispersed $SiO_2$ (SOP) films were prepared by RF co-sputtering method using Pt and $SiO_2$ targets in Ar atmosphere. The growth rate and Pt content in the film were controlled by means of manipulating the RF power of Pt target while that of $SiO_2$ was fixed. The roughness of the film was increased with increasing the power of Pt target, which was mainly due to the increment of the size and planar density of Pt nanopowder. It was revealed that SOP film formed at 10, 15, 20 W of Pt power contained 2.3, 2.7, and 3.0 nm of spherical Pt nanopowder, respectively. Electrical conductivity of SOP films was exponentially increased with increasing Pt power as one can expect. Interestingly, conductivity of SOP films from Hall effect measurement was greater than that from DC I-V measurement, which was explained by the significant increase of electron density.

대기압 열플라즈마 CVD 에 의한 다이아몬드 합성

이재호,고명완,박동화 ( Jae Ho Lee,Myung Wan Ko,Dong Wha Park ) 한국공업화학회 1994 공업화학 Vol.5 No.1

아르곤 열플라즈마 CVD장치를 제작하여 메탄과 수소기체의 화학적인 반응을 이용해서 대기압하에서 몰리브덴 기판에 준안정상(metastaable state)의 다이아몬드를 합성하였다. 증착실험 후 SEM관찰, X선 회절 및 Raman분광분석을 행한 결과, 기판표면온도와 수소에 대한 메탄 농도비에 따라 증착 입자의 morphology가 변화하였다. 본 연구에서 설정한 중착조건 범위에서, 다이아몬드는 기판표면의 온도가 약 890℃와 수소에 대한 메탄 농도비가 0.5%로 하였을 때, 결정성, 밀도 및 품질이 우수한 다이아몬드 입자를 합성하는 것이 가능하였다. In an argon thermal plasma CVD system, diamond of metastable state was synthesized on molybdenum substrate by chemical reaction of methane and hydrogen under atmospheric pressure. The analyses of SEM, XRD and Raman Spectra shows that the morphology of deposited particle was transformed according to surface temperature of substrate and concentration ratio of methane to hydrogen. Diamond was relatively well obtained when surface temperature of substrate was 890℃ and concentration of methane ratio was 0.5 percents.